How can this be an open source

I was reading one British Linux magazine when I ran accross this amazing tool for surveyers and land planners. I can not believe that they've made it an open source - years ago people used to pay huge bucks for it. The tool is called GRASS, and it is available at
www.grass.itc.it . It is used for 2 and 3-Dimensional terrain mapping, land planning, distance calculations, and relief representation. If was originally used by the military for mission planning and accurate relief representation, and it is now donated for an open source use. I can think of at least three or four type of business or consulting services that could use this tool for commercial purposes - land planners, surveyers, developers, transportation services, ... I would recommend this free tool to anyone who is interested in land planning and development. Imagine starting the new business with unlimited licenses of AutoCAD. Not bad, not bad at all.